Introduction: Conduit Bike Trailer

Picture of Conduit Bike Trailer

Build a nice bike trailer out of a piece of electrical conduit and some old bike bits

Step 1: What You Need

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Two bike forks
wheels for the forks
A piece of 10' steel electrical conduit that can fit (snuggly-ish)over the head of the bike fork. 1" conduit worked for me
A piece of thinner conduit, also steel. This is to make a brace or two
A sturdy piece of wood. I initially used a broomstick, which prompty shattered. A 2x3 worked (and is still working...)
Two old bike inner tubes. Get these from the dumpster behind a bike store, or your enemies' bikes

the plumbing pipes in the picture have nothing to do with the project--they're just living their lives, not bothering anybody, so I say, live and let live, right?

Step 2: Ways to Build It

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I can think of three ways to assemble this, all of which would work pretty well.
The differences are how you attach the bits of conduit to one another.

You could:
Lash with inner tubes

I used a MIG welder, because I wanted welding practice. If you wanted to bolt instead, every time I weld two pieces together, you would drill a hole through them and stick a bolt through it. You'll probably want to whack the conduit a bit where you'll be drilling to flatten it out.
If you're lashing, then just lash, man.

If you're welding, be sure that you don't have galvanized conduit. Seriously--welding galvanized steel frees criminal molecules that had been locked up in their metallic prison, and the criminal molecules run through the air into your lungs and try to kill you. So seriously, don't weld galvanized stuff.

also, if you're welding, make sure all your conduit is steel. Otherwise it probably won't work.

Step 3: Bend the Conduit.

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Take the 1" conduit, and bend it to make a
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kind of shape. There are several instructables on how to bend tubing. I tried to cheat and shape my tubing around a restaurant's oil drum, and ended up crimping it by mistake, but the conduit's still strong in the direction that it will get stressed.

Here's Ricketts, modeling with the bent conduit. It's really an ugly bend. I'm sorry :(

Step 4: Attach the Forks

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Take your bike forks (keep the wheels off them for now) and stick them into the open ends of the conduit. Use your preferred method of attaching them. Take a second to make sure they're aligned with eachother, and that they're perpendicular to the ground.

Step 5: BRACE!

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Use a hacksaw, pipe cutter, or grinder to cut a piece off the other conduit that will brace across your frame. Attach it near the wheels.
The picture's pretty self-explanatory, I think

Step 6: Lengthwise Thingy

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Now, cut another piece of conduit that can run length-wise. This isn't very structural, but it's handy to attach things to them when you want to trail around.
Attach it down the center of the frame.

I made mine really long originally, thinking that I could use it as the tongue that attaches to the bike. Then I remembered that conduit can bend pretty easily and cut it off at the top of the frame

Step 7: Put the Wheels On

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Step 8: La Lingua

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The tongue is the piece of wood that will attach to your bike. You probably want 3 feet or so between the bike and the trailer, and then overlap a couple of feet (or more!) with the conduit running down the center of the frame.
Use a piece of inner tube to lash the tongue to the conduit.

Step 9: Attach It to Da Bike

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Now, attach the tongue to your bike seat with another inner tube. Lash it tightly.

Step 10: Done!

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sweet, you're done
Go bike around and haul things.
I'm pretty sure I wouldn't trust it with a human's weight, but I used this trailer to carry my laundry to and from the laundromat, and also to shlepp 2 4x8 sheets of plywood a couple of miles, and it's worked really well so far.


alex hornstein


Brother_Bear (author)2006-07-17

Breathing in the fumes from welding galvanized steel and iron doesn´t kill you it only makes you sick enough to wish it did. Here in sweden its called "Galv-frossa" which means literly the "galvanized-shakes" but a better expression would probably be "the Zink-shakes" beacuse its the fumes from the heated Zink-layer that is the culprit. Its quite common among foundry/steel-workers who work with galvanised steel here in sweden and they supossedly build up an immunity to the shakes over time.

jsadler1 (author)Brother_Bear2016-01-10

In the US, it is usually called zinc shakes. It may be mild and a few minutes walking it off might do. But it can be quite serious and I am in favor of calling an ambulance just in case. I really doubt that anyone become immune to it. I suspect that most people who weld get smarter and use better ventilation after they get a mild dose of zinc shakes.

prank (author)Brother_Bear2006-07-18

Yeah, but if you're in an area with crappy ventilation, I heard it can wreak havoc with your system. An interesting thing a friend was telling me--In the US, Galv-frossa is called Monday Night Fever. Professional welders can get a tolerance for zinc fumes over time, so during the week, when they are constantly exposed to fumes, they are pretty immune to it, but over the weekend, their tolerance drops back down, so they all get sick monday night. The first time I welded, I got horrible flu-like symptoms within about an hour. I was welding bike tubing, so I still don't know what caused it, since I don't think that it's galvanized. Maybe I missed some paint when I was grinding a clear spot to weld, and breathed paint vapors. Anyway, it sucked.

sleeping_gecko (author)2006-08-17

I've not done much with innertube lashing, so I don't know how much friction it would provide for the hole here. I was thinking you might want to drill a hole 6" or so from the end of the wood (6" from the front), and put a nail (with the point filed/ground off) through it. You could bend a rounded 90 degree angle into it, so it could hook around your seatpost a bit. This might be a good idea (especially with heavier loads).

jsadler1 (author)sleeping_gecko2016-01-10

I have lashed with inner tubes and they can be quite strong. Usually, you'll need more inner tubes than you would expect to use.

prank (author)sleeping_gecko2006-12-07

I've pulled ~300 pound loads with innertube lashings without a problem. Innertubes have so much friction that they can hold pieces together incredibly well. Just be sure to lash them tightly

sleeping_gecko (author)prank2006-12-08

That's quite a substantial load. I was seriously considering building one of these, but I'm in a dorm building on a college campus, and my spare bike parts are at home, so I don't have them with me and I have no place to store it.

And then, a few months ago, my bike got stolen. It was right after I put on the chrome fenders that I had brought back from the junk bike I bought in Japan when I was there, too. But other than that, it didn't have much worth left to it other than being an abusable college-student bike (front derailer=gone, rear derailer=3 or 4 gears, instead of 5, depending on its mood, rear brake=gone, a spoke or two on the rear wheel=gone, tires and most of the non-painted parts=crapped up and nasty from the better part of a year and a half of sitting outside through rain, snow, freezing cold, boiling heat).

I miss it though. I do a lot of walking now. I loved riding in snow last winter.

ckassor (author)2007-05-16

if you don't want to weld the forks into the frame, how else could you do it securely? i'm thinking of making a trailer similar to this, but out of pvc pipe. i don't know how to keep the forks secure, though.

prank (author)ckassor2007-05-16

I'd drill a hole through the fork and the pvc pipe, line up the holes and throw a bolt through them with some nice wide washers and a lockwasher to keep the nut from coming loose

jsadler1 (author)prank2016-01-10

You might want to try a nylon type of nut with the steel threads. I believe they are called nylock nuts.

Yerboogieman (author)ckassor2009-02-20

PVC forks with bolted on wheels.

tigerboy (author)ckassor2008-05-20

90 degree elbow for either pvc or black pipe the blackish pipe

remal boon (author)2010-01-24

Industrial tube benders have springs that go inside the tube to stop it crimping. I think you can also protect it by filling the tube with sand before you bend it. The principle is just to get something flexible enough to bend inside the tube but which will resist the tube being compressed.

jsadler1 (author)remal boon2016-01-10

Spring benders are used on the outside of small tubing to control the bend. The spring is the bender. For high-quality work, a mixture of water and a bit of dish soap is frozen inside a tube before it is bent. That keeps it round. Sand can be used but must be tamped down in the tube in such a way that it has no place to move about So it is best to seal the ends, then bend, then remove the sand. But the old time way may be the best way. Use caution and fill the tube with molten lead. When it cools make the bend. Then heat the tube to capture the melting lead into a container. Molten lead is best handled by adults who have some experience as you can be seriously injured or killed.

Gary James (author)2010-05-03

if you don't want to weld the forks into the frame, how else could you do it securely? i'm thinking of making a trailer similar to this, but out of pvc pipe. i don't know how to keep the forks secure, though.

2 stroke (author)Gary James2010-09-02

drill a hot through the fork stem and pvc strait and put a bolt and a llock nut to hold it i dont know a bout pvc i know it is weak and flexable you probable will want to sue wood or steel pip and rent or buy a cheap welder the wlder will e useful for other stuff too

mattbomb (author)2010-07-23

dude now this is making use of what ya got. this is great man. awesome trailer design

curley1 (author)2009-09-25

Lol! That's the first one I've seen hauling a full sheet of plywood. I like the simplicity of this low cost design. Have you tried to make a single wheel trailer out of conduit?

curley1 (author)2009-09-25

You could use 1" conduit clamps to attach it. Either through-bolted or with big wood screws.

sayoian99 (author)2009-05-23

good tip...jk! but seriously,not half bad.

gweedoh! (author)2008-05-26

this looks awesome. I need to build a bike trailer for haulin stuff. I like the bike forks on the back. wildly practical.

a6t1wzbk0tb (author)2007-07-13

fill the bend area with sand to prevent flattening make multiple passes

SpaceRat (author)2007-02-25

Incredibly ingenius use of an old inner tube. Some folks would have gone to great lengths to come up with a nuts-and-bolts approach to attaching the tongue, whereas you have accomplished it quick, easy, and much faster. Well done!

motwnbro (author)2006-08-23

i made a trailer for my sons tricycle using conduit tibes. after bending the two tube in an s shape that i wanted (think flat shape), setting the at an angle to each other (think v shape). gave the frame a more refined /three dimensional appearence.

sleeping_gecko (author)2006-08-17

Dude, this is about 99% freaking awesome. And 1% butterscotch ripple.

somerwaters (author)2006-07-25

yea, Bending conduit can be frustrating. if you don't have a friendly electrician around whose 1" pipe bender you could borrow, you can use the crook of a tree or two structural pieces of a iron fence about 2-6 inches apart. the narrower the easier, then every 1/2 inch give the pipe a shove and bend it about 20 degree's. you do that 4 times and you have your 90 degree bend(don't worry about the math there:I) NOTE the wider the crook of the tree, the smaller a bend you make, otherwise you still can crimp the pipe, so find some TIGHT CRACK between some structural steel. a good place is in the frame work of a billboard sign...

iecreativeartworks (author)2006-07-25

combat zinc poisoning with lots of MILK!! Yumm!

trebuchet03 (author)2006-07-17

I'm not a big fan of mounting the trailer that high (just for stability reasons) -- but nice work ;)

mikesty (author)trebuchet032006-07-17

Agreed. Prank, you ought to build a doodad that attaches to the seat post and I guess the axel of the rear wheel and makes sort of a triangle. The trailer would be more stable, be far more flat (however flat you'd like it to be), and you'd probably have an easier time making turns. Just a simple cross piece that clears the back wheel and is lowered a bit.

mikesty (author)mikesty2006-07-18

That's pretty inspiring. I also read your blurb on how to save energy by cutting the brakes on the bike. Simply genius.

prank (author)mikesty2006-07-18

That sounds like a totally good idea. As far as stability goes, though, my preferred technique is to ride ricockulously unstable bikes to begin with, such that they really can't get any worse. I think it gives me a more optimistic view of life....

gpd209 (author)2006-07-17

butt ugly, but very functional. I like it! You should do something to feature the very interesting bicycle designs I see in the background of a couple of shots here.

prank (author)gpd2092006-07-17

I might post a project on how to chop a bike. Usually I don't really plan it as a project, I just grab a welder and start wreaking havoc, but that would be cool.

mikesty (author)prank2006-07-17

That definitely would be cool. I lack a welder, but I have about half a dozen or more bikes in my garage. My neighbors just come over and leave their crap at our house - we've got some of their cups in the cabinet. I think they'd like it if I welded together their bikes, or turned it into a trailer.

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